t9100: don't use symlinks with SVN on MINGW

The SVN library doesn't seem to support symlinks, even if symlinks are
enabled in MSys and Git. Use 'cp' instead of 'ln -s'.

Signed-off-by: Karsten Blees <blees@dcon.de>

t/t9100-git-svn-basic.sh

@@ -25,7 +25,14 @@ test_expect_success \
 	(
 		cd import &&
 		echo foo >foo &&
-		ln -s foo foo.link
+		if test_have_prereq !MINGW
+		then
+			ln -s foo foo.link
+		else
+			# MSYS libsvn does not support symlinks, so always use cp, even if
+			# ln -s actually works
+			cp foo foo.link
+		fi
 		mkdir -p dir/a/b/c/d/e &&
 		echo "deep dir" >dir/a/b/c/d/e/file &&
 		mkdir bar &&